Scheme for Unimolecular Decompositions

At pressures sufficiently high that Mfe kr(Em), where hiEm) represents the mean rate constant, we have the high concentration limit for R/ 

By using the RRK theory we see that ke Vs= lO sec , since it represents a unimolecuUir process that requires no activation energy. On the other hand, fc, == v(l — so that, setting Vs = Vr [since the 

In the usual case when E is greater than zero we can expect kr K ks and F Z) = l. In the event that E is close to zero, as might be expected when A and B are free radicals, we can neglect the deactivation step for A and B and set Ks = 0. 

In addition, Mfcg, the rate of collisional deactivation of [AB], will be very much less than either ks or kr (see footnotes on page 240), so that F Z) is 

At relatively high total concentration (Mfc2 fcr) this has the value (1 + fcr /fce)- = since in this case fce = /v, and at very low total concentrations (Mfc2 fcr) the value unity. 

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